Field of the Invention
The present invention relates to a core discharge device and a core discharge method, and more particularly, to a core discharge device and a core discharge method that facilitate the breaking of a core inside a cast material.
Background Information
When casting a hollow article and the like, a sand core formed by hardening a casting sand with a binder is placed in a metal mold and a molten metal is supplied thereto; when the molten metal is solidified, the cast material is removed from the metal mold, and the sand core inside the cast material is destroyed by application of an impact force to carry out discharge.
Examples of binders for hardening the casting sand described above include organic binders that use a phenol resin or the like, and inorganic binders that use water glass.
As described above, in a method in which the sand core is destroyed by application of an impact force to the cast material, the sand core is destroyed and gradually discharged from a sand discharge opening by repeated application of impact force. However, it is necessary to apply at least a predetermined impact force in order to discharge the sand core. In addition, if the density of the casting sand that remains inside the cast material is reduced with the discharge of the casting sand, a void is generated in the cast material and there will be no support from the inside; therefore, if a constant impact force is repeatedly applied, there are cases in which the cast molded article undergoes plastic deformation or is destroyed.
Patent Document 1 (Japanese Laid-Open Patent Application No. Hei 7 (1995)-314125) discloses striking a cast material by a predetermined impact force to destroy the sand core, after which the casting sand is discharged by striking with an impact force that is smaller than the predetermined impact force.
In addition, Patent Document 2 (Japanese Laid-Open Patent Application No. Hei 9 (1997)-174194) discloses destroying the sand core by submerging the sand core, which is formed with a binder containing water glass, in water after casting.